Adolescents' attitudes toward disadvantaged groups are surprisingly understudied. What we know from these few studies is that adolescents' attitudes tend to become more favorable over time and that adolescent girls display more favorable attitudes than do adolescent boys. However, researchers have not offered explanations for why these effects occur. We proposed that changes in social-cognitive abilities that accompany adolescent development increase perspective taking and that the increased perspective taking facilitates more favorable attitudes toward disadvantaged groups. Because girls develop social-cognitive abilities earlier than boys, girls should show greater perspective taking and thus more positive attitudes toward disadvantaged groups than should boys. Importantly, we propose that these more positive attitudes are explained better by perspective taking than by gender. Participants were late adolescents (n = 803, 53.3 % female, ages 15-19) from high schools in north-central Florida (United States) participating in an ongoing, multi-wave study. Participants completed a measure of perspective-taking and reported their attitudes toward three disadvantaged groups (Black, gay, and poor people) during their third year of high school and, again, 6 months later during their fourth year of high school. Our findings provided strong support for our theorizing. Girls generally reported warmer attitudes than did boys toward disadvantaged groups, with the gender differences in warmth tending to diminish across time. Similarly, girls were higher than boys in perspective-taking abilities at both time points, although boys increased over time whereas girls did not. Crucially, perspective taking mediated observed gender differences in attitudes, suggesting that perspective taking is a mechanism for improving attitudes toward disadvantaged groups during late adolescence.